The Japanese word ko when written in the Kanji form 子, means child. Thus the Japanese name is a reference to the Microchu being the Ochu's "children".

[view·edit·purge]"Ochu" comes from Dungeons & Dragons; specifically, it is the otyugh. The name in Japanese (and transliterations) comes from the pronunciation; it is pronounced with a short O and T (practically to a ch), making the pronunciation close to "o-chuugh". "オチュー" is the closest the katakana system can get to representing the sound without using compound katakana pronunciations not natively found in Japanese.